This invention relates generally to optical data communication devices and, more specifically, may relate to optical signal transceiver units that transmit and receive optical signals in digitized form in order to share data and/or communicate that data between computers and servers, over routers, switches and networks.
Opto-electronic devices such as photo-detectors and lasers convert signals between optical and electronic forms. Opto-electronic transceivers that generate and receive digital optical signals in computers, servers, routers or switches are essential sub-assemblies of such communications systems. Opto-electronic transceivers are assemblies of optical, electronic and opto-electronic components. The opto-electronic devices in the transceivers create and receive digital optical signals under electronic signal control by converting electronic signals into digital optical signals for transmission over fiber optic cables and networks; these devices also function by receiving and converting digital optical signals into electronic digital signals for use by the host computers, servers, routers or switches. Inasmuch as the size of the components of a transceiver assembly is very small in a transceiver assembly, a controlled environment is mandatory for components within which to exist and operate efficiently and reliably.
A transmit optical subassembly or TOSA typically comprises, at least, a minimum of a solid-state laser device and a light transmission conductor along with conventional data signal electronic control circuits. These circuits control and drive a solid-state laser in order to generate light pulses under an electronic control. The receive optical subassembly or ROSA, at a minimum, is similarly constituted of a photo-detector and a light transmission conductor together with electronic circuits necessary both to convert the output of a photo-detector into usable electronic data signals and to transmit and condition the output signals of a photo-detector. The photo-detector output signals are generated by light pulses impinged on the detection surface of a photo-detector by an associated light transmission conductor.
Typically, optical data signal conductors are optical fibers. The digital light signals are conducted into and out of a transceiver assembly by very small optical fibers, in the order of 8-10 microns in diameter. Similarly, the exit or the light projection aperture of a solid-state laser is commensurately small. The photo-detector detection surface may be larger so that all of the light of the incoming digital signal impinges on the detection surface, thereby insuring reliable reception of the optical signals. With the diameter of an optical fiber being 8-10 microns, the placement of and quality of the pulses of light are critical. Light signals must not be attenuated or degraded by contaminants on any of the optical fiber end faces, surfaces of lenses, surfaces of reflection suppressors, faces of the opto-electronic components, or in the atmospheric light path.
Very significant efforts are made to create extremely accurate alignments of the optical elements of the system. In more enhanced systems, the digitized optical signal may be passed through one or more lenses and an anti-reflection isolator, and then may be reflected off angled surfaces on the end of an optical fiber to direct, control and position the light pulses properly relative to other optical elements of the system.
Contaminants introduced into or allowed to enter the internal environment of a transceiver module may include dust particles, water vapor or condensate, dust, fumes, smoke or other pollutants. Such contaminants may reduce the light signal transmission strength sufficiently to render the transceiver unreliable in either or both the xe2x80x9ctransmitxe2x80x9d or xe2x80x9creceivexe2x80x9d modes of operation.
One micron particles of dust, debris or other contaminants that settle on or are attracted to the optical surfaces, which coat or block even a portion of the light path, will greatly diminish the optical strength of a signal passing to or from the opto-electronic element. Similarly, if there are lenses or other optical elements in the light path, each of these optical elements may collect dust, particulate contamination, moisture, or a film of contamination on any or all the optical surfaces thereof, and thus prevent the efficient passage of light therethrough.
Lasers are very sensitive to moisture; moreover, reflective coatings on facets of some types of lasers, such as a DFB (distributed feedback) laser, are sensitive to condensed moisture as the condensate acts to interfere with the passage of the laser signals therethrough.
With the use of an hermetic seal on the container of the opto-electronic unit, final assembly of the unit may be a accomplished under very controlled humidity conditions. By eliminating the possibility of moisture in the TOSA or the ROSA, the laser is protected and reliability is increased.
Accordingly, in order to exclude all contaminants, the environment within which a transmit optical subassembly (TOSA) or receive optical subassembly (ROSA) operates must be closely controlled during manufacture and assembly periods. The module or containment structure which encloses the TOSA and ROSA must block and prevent introduction of contaminants to prevent internal contamination after assembly in order to assure reliable operation that has been designed into the TOSA or ROSA by means of very precise placement of the optical and opto-electronic components within the transceiver module. Otherwise, contamination of the transceiver module interior reduces or destroys benefits of the efforts to establish and maintain accurate alignment of the various optical and opto-electronic components of the assembly.
It is an object of the invention to control the environment within an opto-electronic module.
It is a further object of the invention to exclude and prevent all contaminants from entering the internal environment of an opto-electronic module.
It is another object of the invention to prevent debris or contaminants from interfering with the proper operation of the optical devices of an opto-electronic module. It is a still further object of the invention to hermetically seal the exterior container structure of an opto-electronic module.
Other Objects of the Invention will become apparent to one of skill in the art upon acquiring a complete understanding of the invention
The foregoing Objects of the Invention are exemplary and not intended to be limiting of the scope of the invention in any manner.